All right, we're now going to hear a doctor describing what's going to happen to a patient during a cutting-edge medical procedure.

JAMES STEEIL: So Karl's going to come in through this door. We'll put him down on the ground, restrain him.

UNIDENTIFIED WOMAN #1: Here he is. Chris (ph)?

STEEIL: ...Induce him under anesthesia. To do that, we have to put a bag over his head.

MARTIN: Karl is a bird. He's one of the animals living at the National Zoo here in Washington, D.C. And as NPR's Neda Ulaby reports, vets there had a problem. Karl's long, pointy beak was worn down, and he could not catch bugs.

NEDA ULABY, BYLINE: We're in an animal operating room with six zoo workers and one Abyssinian ground hornbill, Karl.

STEEIL: We'll lay him down, and we'll see what he does.

ULABY: Veterinarian James Steeil says this operation came from a Smithsonian Institution collaboration with the Natural History Museum. They found a skeleton there from another hornbill who lived in the zoo in the 1930s. They used a 3-D printer to copy that dead bird's beak and make Karl a new one. Now they're about to attach it.

STEEIL: So Neda, I don't know how much bird anesthesia you have seen, but for the most part, they do an excitatory phase.

UNIDENTIFIED WOMAN #1: He is flapping.

ULABY: Soon, the bird goes limp.

STEEIL: You're all right, Karl. All right, Gil (ph), can you hold the body?

ULABY: Karl is about the size of a small turkey. His feathers look like crushed black velvet up close, and his surprisingly long eyelashes are a little like a Muppet's. Vets, keepers and volunteers monitor Karl's heart, check his temperature. And while he's unconscious, they trim his wide flight feathers and groom his gnarly claws.

UNIDENTIFIED WOMAN #2: His feet are cold.

STEEIL: I'm going to trim some of his upper bill, just where it looks a little jagged.

ULABY: It took six months of tinkering before the team at the National Zoo figured out the right weight, and heft and shape for Karl's new, plastic beak. This is their second try at fixing it. Beak No. 1 fell off about a month ago. This time, they're using glue meant for animal hooves. Zookeeper Deb Grupenhoff says Karl was super excited when the first bill was attached. Usually, he's more restrained.

DEB GRUPENHOFF: He's more of a gentleman, but he kind of controls the yard he's in, and he's constantly hunting the entire day. So he's walking around, checking everything out, monitoring his area.

ULABY: Within a few hours, Karl was back on his scaly, black feet, hunting, and pecking and showing off his 3-D-printed prosthetic beak to visitors at the National Zoo. Neda Ulaby, NPR News, Washington. Transcript provided by NPR, Copyright NPR.